The invention is in the field of combination products derived from solid with liquid hydrocarbons, particularly the combination of coal with crude oil, in order to create a combined product that may be subject to further refining and processing. In particular, the invention is in the field of introduction of solid hydrocarbons, such as coal, into the crude oil refining process in order to upgrade the solid hydrocarbon and replace a proportion of the crude oil in the refining stream.
Coal fines and ultrafines, including microfines are the small particles of coal generated from larger lumps of coal during the mining and preparation process. While coal fines retain the same energy potential of coal they are generally considered a waste product as the particulate nature of the product renders it difficult to market and transport. Coal fines are therefore generally discarded as spoil close to the colliery forming large waste heaps or contained in large ponds that require careful future management in order to avoid environmental contamination or even the threat to human life as demonstrated in the 1966 Aberfan disaster in South Wales, UK.
Nevertheless, coal fines do offer a cheap and plentiful supply of hydrocarbons particularly rich in carbon. It is known to add slurries of coal fines in water to fuel oils in order to upgrade the coal fine product and reduce the cost per unit volume of the blended fuel oil (see for example U.S. Pat. Nos. 5,096,461, 5,902,359 and 4,239,426). However, in its natural state, coal fines typically contain significant levels of ash-forming components that would render it unsuitable for blending with crude oil. Furthermore, the amount of water present in coal fines (ca. 35% by mass or % m) is also undesirable for use in crude oil. In addition, the sulphur content of coal fines is commensurate with that of crude oil, however lower sulphur crudes are valued more than high sulphur crudes, so any means to reduce sulphur in coal for use with crude oil is desirable. Selecting coal fines with low mineral matter content is one possibility for ameliorating these problems and can be manufactured by crushing and grinding seam coals that are selected to have an inherently low mineral matter content (e.g. <5% m), however, this limits quite substantially the types of coal that can be utilised.
Crude oil is classed as a fossil fuel and is a non-renewable energy source. Furthermore, while oil prices are quite volatile the refined products that are obtained from the crude oil are always significantly more expensive. A way in which crude oil could be blended with a cheap waste material, such as coal fines, to extend the finite reserves of crude oil, and the resultant refined distillate products, would be highly desirable.
These and other uses, features and advantages of the invention should be apparent to those skilled in the art from the teachings provided herein.
U.S. Pat. No. 5,503,646 refers to solid-liquid extraction of crude oil-coal mixtures, with emphasis on upgraded coal products and is specific to low rank coal (lignite and sub-bituminous coal). U.S. Pat. No. 5,503,646 utilises coarse coal particles (150-250 microns (μm)), and solid-liquid extraction techniques to separate solid product from heated slurry. U.S. Pat. No. 5,503,646 does not use distillation.
U.S. Pat. Nos. 5,096,461, 5,902,359, 4,239,426 and 4,309,269 all refer to processes for mixtures of coal and crude oil, as well as water, to enable coal pipeline transportation. U.S. Pat. No. 4,309,269 refers to dissolution of coal within a crude oil-coal slurry, albeit at high pressure.
U.S. Pat. No. 4,900,429 describes a process for manufacturing a synthetic crude by hydrocracking heavy oil, crushed coal and pyrolysed coal volatiles.
JPS54129008, JPS5636589 and JP S5798595 refer to stable dispersions of crude oil and pulverised coal (particle size 50-100 μm) with surfactants. JP2000290673 and U.S. Pat. No. 7,431,744 refer to processes for increasing calorific value of coal by adding crude oil as a slurry or a briquette.
Curtis, C. W. et al. (Evaluation of process parameter for combined processing of coal with heavy crudes and residua (Ind. Eng. Chem. Process Des. Dev., 1985, 24, 1259)) covers co-processing of coal and petroleum crudes/residues in the temperature range 375-475° C., but with a requirement for hydrogen under pressure and with a catalyst. Fractions were solvent extracted and not distilled. CN105567321 and CN101649220 provide other variations of coal liquefaction technology using crude oil as the liquefying solvent, but requiring a catalytic high pressurized hydrogenation unit. Resultant products were solvent extracted, not distilled. Such processes are energy intensive and rely on the presence of a hydrogen atmosphere and catalyst which, if absent, severely reduces conversions of coal to such low yields of upgraded products as to be commercially non-viable.
British Coal Corporation, CEC report EUR 18247 (Improvements to direct coal liquefaction, 1999, ISBN 92-828-5444-2) refers to the direct liquefaction of coal by the co-refining with hydrogenated anthracene oil solvent.
Bartle, K. E. and Taylor, N. CEC report EUR 13168 (Co-refining of coal and petroleum, 1991, ISBN 92-826-2220-7) refers to the direct liquefaction of coal by co-refining with heavy petroleum oil-derived fractions and under one-stage, catalytic hydro-liquefaction conditions.
The present invention addresses the problems that exist in the prior art, not least reducing reliance on crude oil as a source of valuable petrochemicals, as well as altering or expanding the range of valuable fractions obtainable from crude hydrocarbonaceous substrates.